They get stuck from inside the caliper rather than just the exposed parts you can see.
Did you use red rubber grease when you cleaned them?
Also, only ever use proper brake cleaning spray on the pistons, there are plenty of other degreaser sprays that can leave a residue and cause problems like sticking.
You've 2 options, they either need stripping down and cleaning with a new set of seals, fluid, etc, or do what i did and buy a fully functioning 2nd hand pair off Flebay.
The reason i did that was to save time and effort, and it only worked out around £10 dearer.
I'm on call for work at weekends so needed the bike in working order.
Saying that, i've just had a look at the prices at the moment and they're a bit more expensive now.
I only paid about £70 for the pair!
Or buy a pair off here for £1000........bargain. :b
http://www.yamahamotorcyclespares.co.uk/...IPER&uID=0
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